Recommendations on a cheap telephoto lens for birds?

[masp]

Thanks for the tips guys. I checked out the Canon 70-200mm f4 and it has glowing reviews. I guess the $650 price is about as good as it gets, though I wonder which teleconverter would work well on it. 2x would get me more reach, but less light and the lens isn't very fast to begin with. 25.2 oz seems pretty big and heavy already, though I hear it is light for it's class. Canon's 55-250mm might be the lightest it gets at 13 oz. It's basically a $250 kit lens, though it gets a good review from SLR Gear for sharpness and CA. A TC is probably not possible on it of course.

Is the Nikon 70-300 basically the Canon 70-200's equivalent? The Nikon is slower, weighs about the same at 26.3 oz, is more compact at 5.6" to 7" and costs $515 at Amazon today. If it's true that you generally get what you pay for, the Canon's IQ is probably slightly better with less CA and distortion, according to SLR Gear. Even so, they say that the Nikon's IQ is acceptable at 300mm. VR is a plus compared to the Canon 70-200. Unlike Nikon, Canon's consumer level 70-300 has a rotating front element so it is probably a worse choice, though it is marginally lighter at 22oz.

Non Canikon lenses:
The Sigmas offer very nice reach, but they weigh in about 4 pounds according to slrgear. Pentax offers the very big and heavy 60-250 DA* (43 oz) in this area. Sony's 16 oz. 75-300 is in the kit lens price range and it's soft at 300mm according to slrgear. The m4/3 and 4/3 options are a bit cheaper and maybe a pound lighter at most (counting the body) than these options, but sharpness deteriorates past 150mm (300mm 35mm equivalent). Slightly slower shutter release with m4/3 may be an issue too. They have higher quality lenses, but these are mostly just as heavy as their bigger competitors. I guess there is no free lunch.

I looked at some of the third party Tamron and Sigma lenses, it seems to be the same pattern, but I didn't notice any standout competitors. The sharp lenses are heavy and the less sharp ones are lighter. Does this cover most of the market, or have I missed anything? I think I've mostly exhausted the market options at this point. One other thing I hadn't looked into is possibly getting a telephoto m42 or Leica M mount lens for a micro four thirds camera. Having to manually pre-focus would be more work, but perhaps I'd get an edge in terms of optics and weight?

F8: Nope, I'm still shopping for a DSLR at this point and comparing various systems for what I want. They all look quite similiar so far. One thing I found is that Nikon can use it's pop-up flash as a master flash, so maybe you save a few bucks on lighting compared to Canon, but otherwise it's looking pretty close.

Michaelaw: Thanks for the input! Are you talking about this lens? What aperture and shutter speeds do you usually use with that lens? slrgear says that it's sharper when stopped down considerably, but of course that requires a lower shutter speed. I suppose it works well on bright sunny days.